NORTH COUNTY -- The start of the fall semester at three North County college campuses has brought a spike in riders on the Sprinter light-rail line and has pushed transit planners to double seating capacity during busy morning and afternoon runs.

Though the North County Transit District, which operates the 22-mile line between Oceanside and Escondido, has had no updated passenger count available -- classes started Monday -- the stops at Cal State San Marcos, Palomar College and MiraCosta College have seen crowds of students streaming off packed trains each morning.

The district does acknowledge a spike in riders.

Judy Garza, a junior at Cal State San Marcos, said she has noticed a dramatic increase in the number of students riding the Sprinter this fall.

"In the spring, there were just a handful, but now when you get on, there are always at least 20 other students there as well," Garza said Thursday, as she waited for a campus shuttle to take her from the Sprinter stop to the main buildings on campus.

"I think people are realizing now that it is cheaper and faster to just ride the train," she said.

Garza, who lives in Ramona, said she drives her car to the Escondido Transit Center on Valley Parkway before getting on the Sprinter. A parking pass at Cal State costs $55 per month, while a subsidized bus and rail pass costs $45.

Sarah Benson, a spokesperson for the transit district, said organizers worked hard over the summer to court college riders, mailing about 25,000 postcards to students urging them to use the Sprinter to get to and from classes this fall.

The district will conduct formal passenger counts in about two weeks to better measure the college-driven increase, Benson said.

"We're going to be monitoring the situation to see how it goes, but we know we have seen a real spike in the mornings and the evenings," she said.

The district has already taken action to help keep Sprinter cars from getting too packed.

Planners decided to double the Sprinter's morning and evening capacity Monday through Friday by doubling the number of cars traveling the line, a move that increases capacity from 226 to 452 passengers per trip. The change also doubles the number of bicycles that can be carried per trip. Benson said double trains will operate from 7:30 to 10:30 a.m. and from 2:30 to 5:30 p.m.

All three campuses have reported significant increases in Sprinter train riders with the start of the fall semester. Of the three, Cal State San Marcos has the best way of counting the increase.

The college provides a free shuttle bus to haul students nearly one mile from the Sprinter Station at La Moree Road and East Barham Drive to its main cluster of buildings. Shuttle drivers keep a running tally of how many students and employees ride the shuttle every day, providing an objective measure of how the number of Sprinter riders has increased from the spring to fall semesters.

Deb Schmidt, the university's transportation manager, said the shuttle carried an average of 68 passengers per day in the spring, but that number jumped to about 250 per day in the first four days of the fall semester.

Schmidt said she expects the campus to sell all 150 of its subsidized monthly transit passes in the first week of classes.

"So far, our numbers indicate a very large increase," Schmidt said.

MiraCosta College reported a similar swell in the number of riders.

Dick Robertson, MiraCosta's vice president of student services, said the community college in Oceanside is considering whether to increase the number of subsidized transit passes it sells each month beyond its current limit of 200.

He added that a large fall enrollment has filled every available parking spot on campus, making the Sprinter more attractive for students who want to avoid the daily hunt for a parking space.

"We're at capacity," Robertson said. "We have no room to park anyone else. It's anecdotal at this point, but there is no doubt we have more students riding public transportation this fall than we did in the spring."

With 30,000 full and part-time students, Palomar College in San Marcos is the Sprinter's largest college customer. At 9:10 a.m. Thursday, the eastbound Sprinter delivered about 100 students to Palomar. Among them was first-year student Asia Russell of Fallbrook, who said she parks at the Vista Transit Center and rides the train to campus.

"It's a lot easier than driving and finding parking," Russell said. "That's why a lot of us are doing it."

The North County Transit District has said for years that the three colleges along the Sprinter's route will be a key constituent in helping the line reach its goal of nearly 12,000 daily boardings by the end of its first year of operation. In June, monitors stationed at each of the Sprinter's 15 stations estimated that the line was carrying 7,659 riders per day.

Contact staff writer Paul Sisson at (760) 901-4087 or psisson@nctimes.com.